Thomas Perez, assistant attorney general for civil rights, and Miami U.S. Attorney Wifredo Ferrer said Thursday the probe will focus on whether there was a "pattern or practice" within the police department that led to violations of constitutional rights. The investigation is not criminal in nature.

The shootings between July 2010 and February 2011 sparked outrage in the Africa-American community. The NAACP and American Civil Liberties Union, among others, demanded a federal investigation.

In 2003, the Justice Department launched an investigation into Miami police tactics after several shootings. But that probe reached no conclusion about whether department policies caused civil rights violations.